The world's top iron ore miners supply about half of world demand each year. Annually set iron ore prices have risen as much as 500 percent since 2002 as suppliers struggle to keep up with consumption.

Here is an overview of key expansion projects:

* Vale (formerly Companhia Vale do Rio Doce):

* Rio Tinto Ltd/Plc will spend $2.15 billion to expand the Corumba mine in Brazil to 12.8 million tonnes from 2.4 million starting in the fourth quarter and is investigating a further expansion to 23.2 million tonnes.

* Rio Tinto also plans to expand the annual production at its Pilbara operations in Western Australia to 220 million tonnes by the end of this year in a wider effort to eventually lift output to 600 million tonnes.

* Longer term, Rio Tinto aims to dig a huge iron ore mine in Simandou in Guinea, which it calls the world's largest known undeveloped iron ore province, containing 2.25 billion tonnes of ore. The first year's production could reach 70 million tonnes under the Rio blueprint.

* BHP Billiton Ltd/Plc Rapid Growth Project 5 was approved in February 2008. It is the company's next step in its phased growth path and will increase overall capacity to more than 200 million tonnes a year starting in 2011.

* Vale (formerly Companhia Vale do Rio Doce), is spending $10.1 billion to develop its Serra Sul iron ore project in Brazil's Para state by the fourth quarter of 2011, adding 90 million tonnes of new production.

* Kumba, aims to boost output by 40 percent over two years. Kumba also has the potential to expand output to 70 million tonnes by 2015, making the African mining house the world's fourth largest producer of lump iron ore by 2014.

* Fortescue Metals Group Ltd forecasts full-year 2008/09 production of 45-55 million tonnes, then gradually rising to 100 million tonnes a year as it develop more of its mines near BHP and Rio operations.

* Geraldton Iron Ore Alliance, comprising eight companies in exploration stages, forecasts projects combined annual production of 45 million tonnes starting by the middle of the next decade following a government decision to allow building of a new west coast port at Oakajee. – China Mining